For the last 10 years, many people have crafted inventions aiming at the assistance of the human mobility in the field of rehabilitation or for specific heavy-duty tasks. Some of them have been designed for the lower extremities, addressing the enhancement or the restoration of the locomotion. Others have been crafted for the upper extremities aiming at the arms' mobility restoration or providing assistance during specific or repetitive tasks. Usually named “Exoskeleton” or “Ectoskeleton”, these types of devices perform their task independently of the body structure, they work “outside” the body without interacting intrinsically with the human body while having a mechanical link in order to “move” in sync with the body structure. Current exoskeletons are not designed for a complete merge with the anatomical structures of the human body for a full biomechanical assistance (kinetics and kinematics) nor are they designed for protecting the body structure against acute and chronic biomechanical traumas during high-demanding activities.
For some exoskeletons, we refer to mechanisms named “Load Ground Transfer Exoskeleton for Lower Extremities”, in which the main function relates to the transfer of a portion of the body load carried by the user (weight and additional accessories) directly to the ground with an articulated mechanism running in parallel with the body structure. These types of devices are mainly dedicated to supporting a confined additional load and to assist the human body in heavy-duty tasks such as carrying a heavy back pack onto the user's shoulder-back body structure. These devices supply the biomechanical energy at their respective joint mechanisms for the support of the body load and then the mechanical transfer the load to the ground.
Current load ground transfer exoskeletons for lower extremities are equipped with a critical element, a pair of foot-plate, used as a mechanical component located at the end of a serial mechanism ensuring the mechanical transfer of the body load to the ground and a ground reaction force sensor for the control of the apparatus. Moreover, all designs found into the here above devices limit the load ground transfer through one biomechanical plan, which is the lateral plan, commonly called the sagital plan.
The use of foot-plates for the load transfer and the control brings up many functional issues. On irregular grounds, the biomechanical stability of the user and the ground reaction force signals are compromised. Also, the user comfort during locomotion is significantly reduced and the complex mobility of the ankle-foot structure is jeopardized during mid- and long-term use. The “one-plan” mechanical architecture offered by these designs diminishes the capacity of the device to properly assist the user in real-life situations. Even though these designs are efficient for load ground transfer into the main biomechanical plan during locomotion, they still do not provide any assistance or support for the transversal rotations (transversal plan) and for balancing movements (frontal plan) of the body, which means that the user, even wearing this type of devices, would work very hard against the load and its inertia during those movements (rotations and balance), which represents a significant part of the locomotion.
The load ground transfer exoskeleton for lower extremities is an adequate solution for carrying extra load in simple environments but becomes irrelevant in the case where the purpose of the supporting device is to augment the biomechanical capacity and to protect the body structure of the human body for the whole locomotion including any complex movements related to highly demanding activities.
Another category of exoskeletons are the devices named “Assistive Orthopedic Devices for Lower and Upper Extremities”. These devices are adequate for rehabilitation while they actively assist the basic mobility of the respective limb. However, current designs do not address the full biomechanical requirements of limbs' mobility. In fact, these designs are not conceived to compensate (in generation and in dissipation) the full kinematics and more specifically the kinetics required to exert efficiently the whole mobility of the said limbs. Moreover, the above-referenced devices do not have the required technical characteristics to allow them to distribute with efficacy the additional biomechanical energy deployed by their respective joint mechanism onto the body structure they are designed to support; resulting into a significant reduction of the mechanical assistance.
A final category of exoskeletons is referred to as “Load Transfer Exoskeletons for the Upper Body”. The main function of these devices is to actively assist the overall mobility of the upper extremities by supplying a certain amount of biomechanical energy at their joint mechanisms and transfer the additional effort to a support element located at the trunk of the human body.
These devices are adequate for upper extremities mobility tasks requiring limited torque. In fact, the capacity of the devices to supply kinetic effort at respective joint mechanism is directly related to the stability level of the support element at the trunk. Thus, the capacity of the proposed designs to fulfill the whole biomechanical requirements of the upper extremities mobility is significantly reduced by the fact that the whole part of the additional energy supplied by the device is entirely transferred to the trunk support element rather than being distributed all around the respective limb which could result to the augmentation of the biomechanical capacity as well as the protection the body structure of the respective limb.
Accordingly, there is a need for a device that maintains, restores and/or enhances the mobility of the human body while not being restrictive in terms of maintenance, restoration and enhancement of biomechanical capacity, and consequently exerts a natural body mobility